Experimental And Numerical Simulation Study On Material And Beam Behaviors Of Concrete Made With Manufactured Sand

With the high speed of urbanization and rapid development of infrastructure construction,natural sand are becoming quite rare.As a good alternative to natural sand,manufactured sand is being paid more and more attention.However,there are significant differences between manufactured sand and natural sand in grain shape,gradation,powder content and fineness modulus.These differences will lead to differences on physical and mechanical properties of concrete made with manufactured sand and natural sand.In this paper,three kinds of manufactured sands and one kind of natural sand were selected and their quality were evaluated according to their properties.Meanwhile,digital image processing technology was used to test sand’s shape and concrete model based on aggregate shape difference was established.Numerical simulation method then was used to test the mechanical properties of these concrete models in order to study the influence of aggregates shape on concrete.In this study,concrete specimens used by different kinds of aggregates were also made to test the influence of manufactured sand on concrete workability,mechanical properties,shrinkage,flexural performance and shear performance.The main conclusions are as follows:(1)In this study,natural sand is rated grade II,manufactured sand C is rated grade I,while manufactured sand B grade III due to its gradation.Manufactured sand A does not comply with the provisions of the current standard due to its high MB value,but it has been used in many structure,so it is reasonable to study it.(2)It has found that the shape of natural sand is more smooth and round through digital image processing technology.The influence of shape on concrete mechanical properties was analyzed though numerical simulation method.It can be concluded that strength of concrete made with manufactured sand is higher than that made with natural sand.(3)Workability of concrete made with natural sand is better than that made with manufactured sand.This implies that aggregates particle shape is a important factor to gurantee the workability of concrete.But sort of strength and long-term shrinkage of concrete made with different aggregates is the same as the sort of qulity of different sands,which proves quality of fine aggregate affects the strength and dry shrinkage performance of concrete.(4)The bending and shear mechanism of reinforced concrete beam made with manufactured sand and natural sand are very similar on the whole.The ultimate bearing capacity of reinforced concrete beam made with manufactured sand calculated in natural sand design method can meet engineering requirement as well.But the anti-cracking capacity of reinforced concrete beam made with natural sand is better than that made with manufactured sand.The cracking load of reinforced concrete beam made with manufactured sand obtained by current calculation method is unsafe and needs to be adjusted.